class Solution {
public:
    int lowestCommonAncestor(TreeNode* root, int o1, int o2)
    {
        if (root == nullptr)
            return -1;
        if (root->val == o1 || root->val == o2)
        {
            return root->val;
        }
        int left = lowestCommonAncestor(root->left, o1, o2);
        int right = lowestCommonAncestor(root->right, o1, o2);
        if (left == -1)
            return right;
        if (right == -1)
            return left;
        return root->val;
    }
};